The present invention relates generally to weather forecasting and warning systems. More particularly, the invention provides a method and apparatus for predicting lightning threats with a high degree of accuracy over geographic areas larger than a point.
Weather prediction techniques have improved greatly in recent years. As weather predictions have become more accurate, businesses have begun to incorporate weather-related analysis into their corporate planning decisions. For example, U.S. Pat. No. 5,832,456 describes a system and method for predicting future retail performance on the basis of weather forecasts. Information concerning tornadoes, hurricanes, severe thunderstorms and the like have been used by utility companies, manufacturing plants, airlines, and other businesses to avoid losses and to reroute vehicles such as airplanes and trucks.
Certain types of businesses, such as electric utilities and cable TV companies, are particularly vulnerable to damage caused by lightning strikes. A lightning strike to a transformer or electric substation can immediately cause power outages for large numbers of utility customers. Electric companies frequently employ additional repair crews when severe lightning storms occur so that damage can be quickly repaired. Unfortunately, predicting where lightning is likely to strike with any real degree of accuracy has proved elusive, thus leaving companies scrambling to deploy repair crews only after lightning damage has occurred.
Conventional systems that attempt to predict where lightning damage is likely to occur typically rely on electrical or radio frequency sensors that detect changes in electrical activity. Such systems generally measure actual electrical activity and try to measure the location of the electrical activity. U.S. Pat. No. 5,140,523 (entitled xe2x80x9cNeural Network for Predicting Lightningxe2x80x9d) uses a neural network coupled to electric field sensors to predict the future location of lightning activity. U.S. Pat. No. 5,771,020 (entitled xe2x80x9cLightning Locating Systemxe2x80x9d) describes a system that detects pulses from lightning discharge using RF energy sensors. U.S. Pat. No. 4,996,473 (entitled xe2x80x9cMicroburst/Windshear Warning Systemxe2x80x9d) discloses a system that relies on various types of RF sensors to detect increases in lightning rates over a period of time. Yet another system, described in U.S. Pat. No. 4,806,851 (xe2x80x9cThunderstorm Sensor and Method of Identifying and Locating Thunderstormsxe2x80x9d), uses an electric field sensor to identify thunderstorms within a given range of the sensor. Television stations broadcast meteorological reports showing historical (e.g., past) movement of thunderstorms (e.g., those containing lightning), but do not show future predicted locations of such thunderstorms.
The aforementioned methods lack sufficient accuracy and robustness to be commercially useful to electric utilities, factories, or other structures that could be impacted by lightning strikes. For example, some systems essentially indicate whether lightning will strike a small number of geographic point sources (e.g., a specific radio transmission tower or power pole). In contrast, some companies, such as an electric utility or a railroad, need to know which portions of a geographically dispersed distribution system are vulnerable to a strike. Other conventional systems rely on the prior existence of lightning strikes to predict where future strikes may occur, thus making them ineffectual for predicting early forming storms for which no lightning has yet occurred. Predicting future lightning strikes based solely on previous actual strikes can also lead to inaccurate results. In short, conventional systems have not proved entirely satisfactory for commercial use.
The invention provides a system and method for predicting areas where lightning strikes are likely to occur by evaluating radar and temperature data. In one variation, radar volume data is analyzed to locate areas where cloud tops extend above a temperature line of about negative ten degrees Celsuis. Areas having cloud tops above that temperature line and a radar reflectivity greater than about 30 dBZ are designated xe2x80x9celectrifiedxe2x80x9d areas with lightning potential. Radar data is tracked across at least two time periods, and an algorithm using an image filtering technique predicts the future location of the lightning potential areas at predetermined time periods (e.g., 10 minutes, 20 minutes, and 30 minutes). A computer display shows the predicted location of the lightning threat areas for the current and future time periods.
In one variation of the invention, predicted lightning threat areas are compared to a database of structures (e.g., power lines, factories, and the like) and superimposed on a computer display to help illustrate where lightning damage is likely to occur. Based on the predicted lightning strike areas, utility companies can deploy repair crews to the most likely damage areas.